An Ellicott City man died over the weekend after an accident on the Tough Mudder obstacle course in West Virginia, the first such death in the three-year history of the outdoor run that bills itself as "probably the toughest event on the planet."

Avishek Sengupta, 28, was with a half-dozen friends on the course Saturday when he encountered the "Walk the Plank" obstacle, in which participants jump into a deep pool of muddy water 15 feet below a wooden platform. Sengupta jumped in but did not resurface and was later flown to Inova Fairfax Hospital in Falls Church, Va., where he was taken off life support Sunday.

The Berkeley County Sheriff's Office in West Virginia is investigating Sengupta's death as an accident, according to Sgt. Ted Snyder, the lead investigator. He said such an investigation is standard after deaths or accidents.

Snyder said Sengupta was taken out of the water by Tough Mudder staff and emergency medical technicians resuscitated him so that his heart was beating and he was breathing, but his brain was "compromised" because of how long he was submerged.

Tough Mudder released a statement Monday extending sympathies to the man's loved ones for their loss. The company said "safety is our top priority."

"As organizers, we take our responsibility to provide a safe event to our participants very seriously," Will Dean, CEO of Tough Mudder, said in the statement. "Tough Mudder is devastated by this tragic accident."

Dan Gemp, Sengupta's best friend, was not at the race but said friends who ran with Sengupta told him it took "four to seven" minutes for a nearby Tough Mudder diver to reach Sengupta.

Ashley Pinakiewicz, a Tough Mudder spokeswoman, declined to comment on how long it took for Sengupta to be rescued. Tough Mudder is cooperating with the local sheriff's office investigation, she said.

Gemp said Sengupta's friends and family are devastated by the loss.

"No one has any clue whether it was avoidable or not," he said.

Gemp said the family does not wish to speak to the news media at this time, and that they are focused on remembering Sengupta and preparing for his funeral this week. Sengupta was a Towson University graduate who worked in the Baltimore area in digital marketing.

"You know that one guy in high school who was friends with everyone, who got all the hugs? That was him," Gemp said. "It's a tragedy that you can't make up."

Tough Mudder races are designed to test participants' physical and mental abilities with a course the company says was designed by the British special forces. Through 20 obstacles on a 10- to 12-mile course, runners dodge live electrical wires, jump over 4-foot-wide mud pits and climb a muddy hill while being sprayed from both sides with high-pressure water hoses.

Some 14,000 people participated in the Tough Mudder event Saturday in Gerrardstown, W.Va., including Ravens coach John Harbaugh and other members of the team's staff. Pinakiewicz, the Tough Mudder spokeswoman, would not comment on whether the event organizers would discontinue or modify the Walk the Plank obstacle and said future races would go on as planned.

Arsham Mirshah, a friend of Sengupta's who accompanied him on the course, said Walk the Plank was the fourth obstacle the group encountered, about an hour after their noon start time.

Mirshah said he was the first in the small group to jump off the wooden platform into the chilly water. As he left the water, Mirshah said, he turned and saw Sengupta jump, but his friend did not resurface. Another teammate was the first to notice.

Sengupta was taken by ambulance to a local hospital, and was taken by helicopter from there to Inova Fairfax Hospital. Friends said dozens of loved ones came to the hospital Sunday before Sengupta was taken off life support.

Tough Mudder says it has hosted 50 such events since 2009 with about 750,000 participants. They have become popular with adventure-seekers, and events planned for the next few weeks in Ohio, Chicago and London are sold out.

The company says Sengupta's is the first death on one of its courses, though injuries have been reported at other Tough Mudder events. The West Virginia event was staffed with about 75 emergency and safety personnel, the company said.

A man died in Texas last year while crossing a river in an outdoor obstacle course similar to Tough Mudder called "The Original Mud Run."

Obstacles in Tough Mudder, including Walk the Plank, are inspected before the race and built after consultation with engineers on safety concerns, Pinakiewicz said.

Participants in the race must sign an extensive waiver acknowledging their awareness of "inherent risks" in the course that can cause permanent disability or death. The form requires signees to "take full responsibility for any and all damages, liabilities, losses, or expenses" they incur as a result of participation.

Mirshah described his longtime friend as a "warm and fuzzy" person, an avid rock climber who didn't curse or drink alcohol.

Sengupta, Mirshah and Gempattended Centennial High School together, and Mirshah said they were still mourning the loss of another former classmate, Valerie Cappelaere Delaney, a Naval Academy graduate who died last month in a training accident in Spokane, Wash.

The group joked about Tough Mudder's risks before they began, and took it slowly through the course.

"We said in the car, 'Well, this will be a successful day if no one gets hurt,' " Mirshah said.